1. Technical Field
The present invention relates to a liquid crystal apparatus and electronic equipment.
2. Related Art
A liquid crystal apparatus is provided with a liquid crystal panel in which a liquid crystal layer is interposed between a pair of substrates. When light is incident to such a liquid crystal apparatus, the liquid crystal material, alignment film, or the like which forms the liquid crystal panel undergoes a photochemical reaction due to the incident light and ionic impurities may be generated as a reaction product. In addition, it is known that ionic impurities also diffuse into the liquid crystal layer from sealing material or a sealant in the manufacturing process of the liquid crystal panel. In particular, in a liquid crystal apparatus used in an optical modulating means (light valve) of a projection-type display apparatus (projector), since the luminous flux density of the incident light is high in comparison with a direct-view-type liquid crystal apparatus, it is necessary to suppress the ionic impurities from influencing the display.
As a means for suppressing the influence of the ionic impurities on the display, for example, JP-T-2007-504488 proposes a liquid crystal display apparatus having an ion removal driving unit which removes ions from a liquid crystal layer in an STN system. A uniform electric field is created in the liquid crystal layer by applying a uniform alternating voltage to the electrodes of the ion removal driving unit of the liquid crystal display apparatus. JP-T-2007-504488 discloses that, as a result, the alignment direction (director) of the liquid crystal molecules in the liquid crystal layer changes and the ions move gradually toward the side in the liquid crystal layer in accordance with the changes in the director so as to be removed to the outside of the display region.
However, although a uniform alternating voltage is applied to the electrodes of the ion removal driving unit to remove the ions from the display region in the liquid crystal display apparatus described in JP-T-2007-504488, there is a concern that, depending on the method for applying the alternating voltage with respect to the electrodes, it will not be possible to apply a uniform alternating electric field to the liquid crystal layer due to the waveform of the alternating voltage being deteriorated.
In addition, in a case where, for example, a region to which the alternating electric field is not applied such as an electric parting is arranged in the liquid crystal layer, there is a concern that this region will block the movement of ionic impurities to the side since a uniform electric field is not easily created in this region.
From the above, there are problems in that the influence of the ionic impurities included in the liquid crystal layer on the display may not be sufficiently suppressed.